Spring loaded locking mechanism for chair pedestal



ot. zo, 1959 G. J. SCHERER SPRING LQADED LOCKING MECHANISM FOR CHAIR FEDE-STAI.

Filed July 7`, 1958 INVENTOR. v Georgel Scherer.

ATTORNEYS,

United States Patent Office 2,909,212 Patented Oct. 20, 1959 SPRING LOADED LOCKING MECHANISM FOR CHAIR PEDESTAL George J. Scherer, Kansas City, Kans., assignor to Cramer Posture Chair Company, Inc., Kansas City, Mo., a corporation of Missouri Application `luly 7, 1958, Serial No. 746,807

2 Claims. (Cl. 155-88) This invention relates to locking mechanism for chair pedestals or the like and more particularly to mechanism for preventing accidental displacement of the locking mechanism during use of the chair.

This invention is an improvement over the locking mechanism disclosed in Patent No. 2,659,413 of November 17, 1953.

Heretofore in locking mechanisms for chair pedestals and the like quite often the plungers of the locking mechanism would become displaced from the openings in the pedestals during use and the chair seat would suddenly be lowered causing discomfort and quite often injury to the user.

It is the principal objects of this invention to provide locking mechanism for chairs or the like wherein the support for the pedestal has an opening in one side thereof for receiving a housing for the plunger element; to provide a plunger element for the housing having ends extending from each end of the housing; to provide openings in one side Wall of the pedestal spaced longitudinally thereof for receiving one end of the plunger when the plunger is in locking position; to provide a head on the outer end of the housing having inwardly tapered side walls and a flat or plane outer end surrounding the plunger which extends therethrough; to provide a lever and means for pivotally mounting the same on the outer end of the plunger; to provide said lever with depending side l walls having outwardly turned portions forming cam surfaces for engagement of the plane surface of the end of said head whereby portions of the lever will cause the cam surfaces to contact said head to withdraw the plunger from the openings in the pedestal so that the pedestal may be moved longitudinally with respect to said support; to provide inwardly turned flanges on said side portions of the lever for engaging the inwardly tapered side walls of said head to prevent said plunger from being moved outwardly in said housing when the lever is at right angles to said housing; and to provide stop means on the lever for engaging said head when the lever is parallel to the plunger, and to provide a device of this character simple and economical to manufacture and eflicient in operation.

In accomplishing these and other objects of the in- Vention, I have provided improved details of structure, the preferred forms of which are illustrated in the accompanying drawings wherein:

Fig. 1 is a side view of a chair to which my locking mechanism is attached.

Fig. 2 is a fragmentary cross sectional view of the locking mechanism attached to the support and pedestal.

Fig. 3 isV a view similar to Fig. 2 with the plunger of the locking mechanism withdrawn from the pedestal.

Fig. 4 is a cross sectional view taken on line 4 4, Fig. 2.

Fig. 5 is a perspective view of the locking mechanism embodying the features of my invention.

Referring more in detail to the drawings.

' port 2 of a base 3 of a chair 4. The tubular support 2 is adapted to receive a pedestal 5 having a groove 6 in one side thereof. Extending inwardly and spaced longitudinally of said groove are a plurality of openings or sockets 7. One side wall near the top of the tubular support 2 is provided with a lateral opening 8 and is threaded near its inner portion as indicated at 9. The opening 8 is offset forming an annular shoulder 10 for a purpose later described. l

The locking mechanism proper consists of a tubular housing 11 shown to be hexagon shaped and has a threaded reduced portion 12, the reduced portion forming a shoulder 13 which engages against the shoulder 10 of the support when the housing is threaded into opening 8 as illustrated in Fig. 3. A, plunger 14 is adapted to be slidably mounted in the tubular housing 11. The plunger 14 has a collar 15 nearone end thereof and the end 16 extending outwardly from the collar is adapted to engage in the openings 7 in the pedestal when the plunger is eX- tended inl that position. The opening 17 in the tubular housing is enlarged as indicated at 18 (Fig. 2) forming an annular shoulder 19 against which one end of a coil spring "20 engages and the other end of the coil spring engages against the collar 15 to urge the plunger in extended position.

The outer end of the housing is provided with a head 21 having a plane surface surrounding the end 22 of the plunger 14 which extends therethrough. The head 21 is tapered inwardly toward the body of the housing as indicated at 23 (Fig. 3) forming an annular groove 24 in said housing. Pivotally mounted on theouter end 22 of the plunger by a pin 25 is a lever 26 having a linger portion 27. The lever is channel shaped and has depending sides 28 and 29 provided with aligned openings 3i) through which the pin 25 extends. Each of the depending sides has forwardly curved ends 31 and 32 and the depending sides and ends are turned laterally outwardly as indicated at 33 and 34 (Fig. 4), forming cammed surfaces for engaging the plane outer surface of the head 21. The laterally turned depending sides and curved ends are thence turned downwardly as indicated at 35 and 36 and inwardly, also as best illustrated in Fig. 4, forming inturned flanges 37 and 38 the edges of which work in the annular groove 24.

The cammed surfaces of the laterally turned portions are also indicated in dotted lines as illustrated in Fig. 3. The body 39 of thelever 26 extends upwardly between the curved sides 31 and 32 forming a stop member 40 which engages the head 21 as illustrated in Fig. 3 when the lever is parallel to the plunger 14.

in assembling the locking mechanism herein described the spring 20 is placed over the outer end of the plunger 14 until one end rests against the collar 15. The plunger is then inserted through the housing 11 from the threaded end thereof until the other end of the spring rests against the shoulder 19 of the opening in the housing. The lever 26 is then fastened to the outer end 22 of the plunger by the pin 25 and the housing is then threaded into the opening 8 of the support as illustrated in Figs. 2, 3 and 4, the shoulder 10 of the housing engaging against the shoulder 8 of the opening in the support and the end 16 of the plunger engages in the groove 6 to prevent rotation of the pedestal when the plunger is disengaged from the openings 7.

In operation of the mechanism assembled as described when the lever 26 is at right angles to the housing 11 4as illustrated in Figs. 2 and 5, the end of the plunger 14 engages in one of the openings 7 thus locking the pedestal in a .predetermined position in the support.

When it is desired to change position of the pedestal, movement of the lever to a position substantially parallel with the housing 11 as illustrated in Fig. 3 withdraws or projects the plunger from the openings 7 so that the pedestal may be moved longitudinally in the support. Withdrawal of the plunger is accomplished by the upper cam surfaces provided by the laterally projected portions 33 and 34 of the curved ends 31 and 32, of the lever. In other words, the cam surfaces will contact the plane surface 22 of the end of the head 21 and the lever being pivoted to the end of the plunger will withdraw the plunger from the openings 7 as the distance between pin 25 and head 21 increases. It will be obvious that the space between the edges of the laterally projected portions 33 and 34 is less than the width of the outer portion of the head to prevent movement of the plunger outwardly without moving the lever to a substantially parallel position. In other words, when the lever is transverse to the housing the plunger cannot be withdrawn.

It will be obvious from the foregoing that I have provided an improved locking mechanism for pedestals of a chair or the like which will prevent accidental displacement of the plunger during use of the chair.

What I claim land desire to secure by Letters Patent is:

1. Locking apparatus for a chair or the like having a tubular support provided with an opening in one side thereof and a pedestal having spaced openings in one side slidable in said support comprising, a tubular housing having an enlarged body portion secured in said opening in the support and extending outwardly therefrom, said body being reduced at its outer end, a head on the outer end of the reduced portion of the housing, a plunger slidably mounted within the housing and having one end projectible into a selected opening in the pedestal and having the opposite end extending outside of the head on the housing, a spring within the housing constantly urging the plunger toward its projected postion, said head having a plane surface on its outer end surrounding said plunger and inwardly tapered side walls forming an annular groove between the head and body portion, a manually operable lever having a nger portion for moving said plunger to an unlocking position, said lever being channel shaped and having a pair of opposite depending side portions pivoted to said outer end of the plunger, each of the side portions having curved end portions opposite the ringer portion and said side and end portions being turned laterally outwardly and thence downwardly and inwardly having spaced edges less than the diameter of the outer portion of the head, the laterally turned portions forming cam shoulders for engaging the plane surfaces of the head to cam the plunger to its unlocked position `against the tension of the spring upon pivotal movement of the lever from a normal position at right angles with respect to the plunger to a position where the lever is parallel with the plunger, said spring moving Ilie plunger to its projected position and camming the lever to its normal position when the lever is released and said inwardly turned edges of said side portions normally resting in said annular groove and engaging the tapered side walls of said head to prevent movement of the plunger to unlocking position when the lever is at right angles with respect to the plunger, and stop means on said lever between the curved ends of said side portions for engaging the side edge of said head to limit movement of said lever toward parallel position to said plunger.

2. In combination with a chair or the like having a tubular support provided with an opening in one side thereof and a pedestal having spaced openings in one side slidable in said support a locking mechanism comprising, a tubular housing having an enlarged body portion secured in said opening in the support and extending outwardly thererom, said body being reduced at its outer end, a head on the outer end of the reduced portion of the housing, a plunger slidably mounted within the housing and having one end projectible into a selected opening in the pedestal and having the opposite end extending outside of the head on the housing, a spring within the housing constantly urging the plunger toward its projected position, said head having a plane surface on its outer end surrounding said plunger and inwardly tapered side walls, a manually operable lever vfor moving said plunger to `an unlocking position, said lever being channel shaped and having la pair of opposite depending side portions pivoted to said outer end of the plunger, each of the side portions having curved end portions and said side and end portions being turned laterally and thence downwardly and inwardly, the laterally turned portions forming cam shoulders for engaging the plane surfaces of the head to cam the plunger to its unlocked position against the tension of the spring upon pivotal movement of the lever from a normal position at right angles with respect to the plunger to a position where the lever is parallel with the plunger, said spring moving the plunger to its projected position and camming the lever to its normal position when the lever is released, and said inwardly turned edges of said side portions forming a space less than the diameter of the outer portion of said head and engaging the tapered side walls of said head to prevent movement of the plunger to unlocking position when the lever is at right angles with respect to the plunger.

References Cited in the le of this patentV UNITED S'I`A'I`ESA PATENTS 595,290 Dowman Dec. 14, 1897 761,568 Wedler May 31, 1904 2,041,684 Anderson May 26, 1936 2,568,988 Childs Sept. 25, 1951 2,659,413 Cramer Nov. 17, 1953 

